Projector-carbon.



UNITED star canon.

WENDELL G. WILCOX, 01? LAKEWOOD, OHIO, ASSIGNOR T0 NATIONAL CARBON COMPANY, OF CLEVELAND, OHIO, A' GORPORATION OF NEW JERSEY.

PROJECTOR-CARBON.

No Drawing.

To all an am it may concern Be it known that I, VVENDELL Gr. Winoox, a citizen of the United States, residing at Lakewood, in the county of Cuyahoga and State of Ohio, have invented a certain new and useful Improvement in Projector-Carbons, of which the following is a full, clear, and exact description.

This invention relates to non-flaming are light electrodes particularly adapted for projection Work.

. The object of the invention is to constitute the electrode or its core so that the crater will not travel to any extentand its temperature will not vary through any wide range.

Many salts and oxids have been used in are light electrodes to increase the candlepower of the arc itself. In the old carbon arc the greater part of the light came from the crater in the electrode. The flaming type of arc lamp, however, derives most of its light from the are itself. Hence, the salts, oXids and other materials added to the electrodes have not been used for the purpose of maintaining the crater in any definite position, or for increasing its temperature. Consequently the flaming arc, though admirably suited for street and other general lighting cannot be used for projection work, as the crater is constantly moving, and the arc itself undergoes so many changes that it is unsuitable for this work. Changes in the candle-power or in the position of 'the crater in a flaming arc lamp are small enough to be of no consequence in street lighting, but the changes are very undesirable when used in projection Work.

It is known that potassium or sodium silicate tends to steady the arc,.but I have found that the steadiness will be increased to a much greater extent if other salts are used in combination with the potassium or sodi:

um silicate. If potassium titano-fluorid (K TiF potassium siiico-fluorid (K,SiF,,) or potassium zircono fiuorid (K,ZrF.,), be used alone or together with potassium silicate the crater of the arc is much more stationary than if potassium silicate is used alone or with any other salts that I have tried out. The temperature of the crater is likewise more constant and the unpleasant flickering on a moving picture screen for instan e is practically eliminated.

Specification of Letters Patent.

Patented June 6, 1916.

Application filed July 2, 1913. Serial No. 777,128.

The electrodes may be made of carbon, such as gas coke, petroleum coke, la-mphlack or other forms of carbon, and may have a core consisting of about 80% of carbon, 19% to 15% potassium silicate and 1% to 5% of either of the liourin compounds above given. instead of using the fluorin salts mentioned alone in combination with the potassium or sodium silicate the three may be combined in varying amounts so that the combination will consist of from 1% to 5% of the core mass.

While it is preferred to place the salts mentioned in the core of the electrode in some cases, it may be desirable to incorporate the salts and the carbon as a homogeneous mixture. However, for moving picture work this would not be the preferred form. The potassium salts have been given as the exan'iples in the previous description, but St. lium salts may also be used either as the silicate or as the fluorid compounds.

For the purpose of this application the terms alkaline and double fiuorid in the claims are intended to cover only those examples disclosed and their equivalents.

While I prefer to use the double fluoride and alkaline silicates within the limits given, these compounds suit the purpose when used within still Wider limits. For instance I have obtained good results when as low as 10% of the silicates hnd as high as 10% of the double fluoride were used.

WENDELL o. WILCQX.

Witnesses:

GLEN P. COWAN, CHARLES W. HILL,

i to 10 parts 

